Printing devices that print a print-target image on a print medium in accordance with movement of the device on the print medium are known.
For example, patent literature (Unexamined Japanese Patent Application Kokai Publication No. H10-35034) discloses a manually-moved printing device that is manually scanned on a recording medium to print on the recording medium. Specifically, as the printing device disclosed in the patent literature is manually scanned on a recording medium by the user, the device ejects ink from the print head to the recording medium in accordance with the amount of movement of the device for printing. Furthermore, when the printing device disclosed in the Patent Literature is scanned in the opposite direction to the ordinary direction, the device decorates printed characters such as making the printed characters in bold or underlining the printed characters.
The printing device disclosed in the Patent Literature decorates the characters that are printed by its own device. On the other hand, there is a demand for application of ink based on a luminance distribution of characters and the like that preexist on the application target, which are not necessarily characters and the like that are printed by its own device.